470 THE MUSCULATURE 



longus and magnus, and the vastus medialis muscles, the femoral vessels and nerve, and the 

 knee-joint. At its insertion its tendon covers the gracilis and semitendinosus. 



Variations. — It may arise from the inguinal ligament or be inserted into the fascia lata, 

 the medial epicondyle, or the capsule of the knee-joint. It may be longitudinally divided into 

 two parts. The tendon of the secondary slip is in such instances usually attached to the capsule 

 of the knee-joint, but sometimes is attached to the fascia over the vastus medialis or to the 

 anterior wall of the adductor canal. More frequently the muscle is partly divided proximally 

 or distally. The secondary tendon of origin may arise from the anterior inferior spine, the 

 ilio-pectineal eminence, etc. The muscle is very rarely absent. It may be crossed by a ten- 

 dinous inscription, or more rarely it is rendered digastric by an intervening tendon. 



The quadriceps femoris (figs. 411, 412). — This, as pointed out above, is composed of the 

 rectus femoris and the vastus lateralis, intermedins, and medialis. 



The rectus femoris (fig. 411). — Origin. — By two tendons. The anterior 'straight' tendon 

 is attached to the anterior inferior spine of the ilium; the posterior 'reflected' tendon to the 

 postero-superior surface of the rim of the acetabulum. The two tendons unite so as to form 

 a small arch above the capsule of the joint. 



Structure and insertion. — From this arch an aponeurotic expansion descends upon the front 

 of the muscle nearly to the middle of the thigh. This expansion is broad above, becomes 

 narrower as it descends, and is continued a short distance as a narrow intramuscular tendon 

 after it disappears from the surface. The tendon of insertion begins on the back of the muscle 

 above the middle of the thigh, expands into a broad aponeurosis, and finally becomes a strong 

 band which is inserted into the proximal border of the patella. The fibre-bundles pass in a bi- 

 penniform manner from the back and sides of the tendon of origin to the front and sides of the 

 tendon of insertion. 



Nerve-supply. — As a rule, two branches enter the muscle. One of these enters the deep 

 surface of the muscle in its upper fourth, and is distributed mainly to the proximal part of the 

 lateral half. The other enters the medial margin of the muscle near the junction of the proxi- 

 mal and middle thirds, and is distributed chiefly to the medial half and distal portion of the 

 muscle. 



The vastus lateralis (vastus externus) (fig. 412). — Origin. — From — (1) the shaft of the 

 femur along the antero-inferior margin of the great trochanter and in front of the gluteal tuber- 

 osity; and (2) the lateral intermuscular septum along the upper half of the linea aspera. 



Insertion. — By a flat tendon into — (1) the proximo-lateral border of the patella; and (2) the 

 front of the lateral condyle of the tibia and the fascia of the leg. 



Structure. — The fibre-bundles arise partly from the bone, partly from an aponeurosis which 

 covers the proximal two-thirds of the muscle, and from the lateral intermuscular septum. They 

 take a parallel course distally in a ventro-medial direction, and are inserted into an aponeurosis 

 which lies on the deep surface of the muscle and receives fibres until within a few centimetres 

 of the patella. Ventrally this aponeurosis fuses with the rectus tendon, laterally with that of 

 the vastus medialis, and dorsally it receives some of the fibre-bundles of the vastus intermedins. 

 Commonly the muscle is distinctly divisible for the greater part of its course into two sheets, 

 a superficial and a deep. The deep sheet is often subdivided into two laminae. 



Nerve-supply. — Usually there are three nerves, one of which, accompanied by blood-vessels, 

 runs on the inner surface of the superficial sheet midway between the tendons of origin and 

 insertion, the second between the two lamina? of the deep layer, and the third passes through 

 the innermost lamina to be distributed in part to the vastus intermedins (crureus) muscle. 



The vastus medialis (vastus internus) (fig. 412). — Origin. — From the whole extent of the 

 medial lip of the linea aspera and from the distal half of the intertrochanteric line. The origin 

 takes place by means of an aponeurosis which is adherent to the tendons of insertion of the 

 adductor muscles. 



Structure and insertion. — The fibre-bundles arise from the deep surface of this aponeurosis 

 and are inserted on the medial surface and mai'gin of a tendon which begins on the deep surface 

 of the muscle about its middle near the lateral margin. On the distal lateral border of the 

 muscle it is inserted into the medial half of the proximal margin of the patella and into the 

 medial condyle of. the tibia and the fascia of the leg. For some distance near the knee the 

 lateral margin of the tendon is united to those of the vastus intermedins (crureus), lateralis 

 (externus) and the rectus. 



Nerve-supply. — The nerve to this muscle descends on its medial surface, often bound up 

 with the saphenous nerve for a part of its course. It gives off successive branches and finally 

 sinks into the muscle substance. These branches enter about midway between the origin and 

 insertion of the fibre-bundles of the muscle. 



The vastus intermedins (crureus) (figs. 409, 412). — Origin. — From (1) the distal half of the 

 lateral margin of the linea aspera and its lateral bifurcation; (2) the antero-lateral surface of the 

 shaft of the femur. Between the origin of the vastus intermedins (crureus) and that of the 

 vastus medialis the shaft of the femur is free from muscle attachment. 



Structure and insertion. — On the ventral surface of the muscle lies an aponeurosis which 

 extends from its proximal fourth to the proximal margin of the patella. The fibre-bundles of 

 the muscle are inserted into the deep surface of this and into the deep surface of the aponeurosis 

 of insertion of the vastus lateralis. The proximal fil)re-bundles descend vertically, the medial 

 and lateral, especially the latter, obliquely to their insertion. Medially the tendon is more or 

 less fused with that of the vastus medialis, and laterally with that of the vastus lateralis. The 

 muscle is composed of mu.sdo lamella? superimposed (toiiccntricully about, tlic shaft of the femur. 

 The deepest, most distal of these is called the articularis genu (subcrureus). The fibre-bundles 

 of this layer are inserted into the capsule of the joint or into the superior margin of the patella. 



Nerve-supply. — Several branches are u.sualjy distributed to tliis muscle. To the lateral 

 region a branch from the nerve to the vastus lateralis is usually given; to the middle of the 

 muscle another branch de.scends from the femoral (anterior crural) nerve; to the medial portion 

 there extend several 'twigs from the nerve to the vastus medialis. 



